Programmable light beam shape altering device using programmable micromirrors

ABSTRACT

A digital micromirror device (“DMD”) is used to alter the shape of light that is projected onto a stage. The DMD selectively reflects some light, thereby shaping the light that is projected onto the stage. The control for the alteration is controlled by an image. That image can be processed, thereby carrying out image processing effects on the shape of the light that is displayed. One preferred application follows the shape of the performer and illuminates the performer using a shape that adaptively follows the performer&#39;s image. This results in a shadowless follow spot.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.09/359,064, filed Jul. 21, 1999, which is a divisional of U.S.application Ser. No. 08/962,237, filed Oct. 31, 1997, now U.S. Pat. No.5,953,151, issued Sep. 14, 1999, which is a divisional of U.S.application Ser. No. 08/598,077, filed Feb. 7, 1996, now U.S. Pat. No.5,828,485.

FIELD OF THE INVENTION

[0002] The present invention relates to a programmable light beamshaping device. More specifically, the present invention teaches acontrol system and micromirror device which can alter the shape of lightbeams passing therethrough, and provide various effects to those shapedlight beams.

BACKGROUND OF THE INVENTION

[0003] It is known in the art to shape a light beam. This has typicallybeen done using an element known as a gobo. A gobo element is usuallyembodied as either a shutter or an etched mask. The gobo shapes thelight beam like a stencil in the projected light.

[0004] Gobos are simple on/off devices: they allow part of the lightbeam to pass, and block other parts to prevent those other parts frompassing. Hence mechanical gobos are very simple devices. Modernlaser-etched gobos go a step further by providing a gray scale effect.

[0005] Typically multiple different gobo shapes are obtained by placingthe gobos are placed into a cassette or the like which is rotated toselect between the different gobos. The gobos themselves can also berotated within the cassette, using the techniques, for example,described in U.S. Pat. Nos. 5,113,332 and 4,891,738.

[0006] All of these techniques, have the drawback that only a limitednumber of gobo shapes can be provided. These gobo shapes must be definedin advance. There is no capability to provide any kind of gray scale inthe system. The resolution of the system is also limited by theresolution of the machining. This system allows no way to switchgradually between different gobo shapes. In addition, moving between onegobo and another is limited by the maximum possible mechanical motionspeed of the gobo-moving element.

[0007] Various patents and literature have suggested using a liquidcrystal as a gobo. For example, U.S. Pat. No. 5,282,121 describes such aliquid crystal device. Our own pending patent application also sosuggests. However, no practical liquid crystal element of this type hasever been developed. The extremely high temperatures caused by blockingsome of this high intensity beam produce enormous amounts of heat. Theprojection gate sometimes must block beams with intensities in excess of10,000 lumens and sometimes as high as 2000 watts. The above-discussedpatent applications discuss various techniques of heat handling.However, because the light energy is passed through a liquid crystalarray, some of the energy must inevitably be stored by the liquidcrystal. Liquid crystal is not inherently capable of storing such heat,and the phases of the liquid crystal, in practice, may be destabilizedby such heat. The amount of cooling required, therefore, has made thisan impractical task. Research continues on how to accomplish this taskmore practically.

[0008] It is an object of the present invention to obviate this problemby providing a digital light beam shape altering device, e.g. a gobo,which operates completely differently than any previous device.Specifically, this device embodies the inventor's understanding thatmany of the heat problems in such a system are obviated if the lightbeam shape altering device would selectively deflect, instead ofblocking, the undesired light.

[0009] The preferred mode of the present invention uses adigitally-controlled micromirror semiconductor device. However, anyselectively-controllable multiple-reflecting element could be used forthis purpose. These special optics are used to create the desired imageusing an array of small-sized mirrors which are movably positioned. Themicromirrors are arranged in an array that will define the eventualimage. The resolution of the image is limited by the size of themicromirrors: here 17 um on a side.

[0010] The mirrors are movable between a first position in which thelight is directed onto the field of a projection lens system, or asecond position in which the light is deflected away from the projectionlens system. The light deflected away from the lens will appear as adark point in the resulting image on the illuminated object. The heatproblem is minimized according to the present invention since themicromirrors reflect the unwanted light rather than absorbing it. Theabsorbed heat is caused by the quantum imperfections of the mirror andany gaps between the mirrors.

[0011] A digital micromirror integrated circuit is currentlymanufactured by Texas Instruments Inc., Dallas, Texas, and is describedin “an overview of Texas Instrument digital micromirror device (DMD) andits application to projection displays”. This application note describesusing a digital micromirror device in a television system. Red, greenand blue as well as intensity grey scales are obtained in this system bymodulating the micromirror device at very high rates of speed. Theinventor recognized that this would operate perfectly to accomplish hisobjectives.

[0012] It is hence an object of the present invention to adapt such adevice which has small-sized movable, digitally controllable mirrorswhich have positions that can be changed relative to one another, to useas a light beam shape altering device in this stage lighting system.

[0013] It is another object of the present invention to use such asystem for previously unheard-of applications. These applicationsinclude active simulation of hard or soft beam edges on the gobo. It isyet another application of the present invention to allow gobocross-fading using time control, special effects and morphing.

[0014] It is yet another object of the present invention to form astroboscopic effect with variable speed and intensity in a stagelighting system. This includes simulation of a flower strobe.

[0015] Yet another object of the present invention is to provide amultiple colored gobo system which can have split colors and rotatingcolors.

[0016] It is yet another object of the present invention to carry outgobo rotation in software, and to allow absolute position and velocitycontrol of the gobo rotation using a time slicing technique.

[0017] Another objective is to allow concentric-shaped images andunsupported images.

[0018] It is yet another object of the invention to provide a controlsystem for the micromirror devices which allows such operation.

[0019] Yet another particularly preferred system is a shadowless followspot, which forms an illuminating beam which is roughly of the sameshape as the performer, and more preferably precisely the same as theperformer. The beam shape of the beam spot also tracks the performer'scurrent outline. The spot light follows the performer as it lights theperformer. This action could be performed manually by an operator or viaan automated tracking system, such as Wybron's autopilot.

[0020] Since the beam does not overlap the performer's body outline, itdoes not cast a shadow of the performer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other objects will be readily understood with referenceto the accompanying drawings, in which:

[0022]FIG. 1 shows a single pixel mirror element of the preferred mode,in its first position;

[0023]FIG. 2 shows the mirror element in its second position;

[0024]FIG. 3 shows the mirror assembly of the present invention and itsassociated optics;

[0025]FIG. 4 shows more detail about the reflection carried out by theDMD of the present invention;

[0026]FIG. 5 shows a block diagram of the control electronics of thepresent invention;

[0027]FIG. 6 shows a flowchart of a typical operation of the presentinvention;

[0028]FIG. 7 shows a flowchart of operation of edge effects operations;

[0029]FIG. 8A shows a flowchart of a first technique of following aperformer on stage;

[0030]FIG. 8B shows a flowchart of a correlation scheme;

[0031]FIG. 8C shows a flowchart of another correlation scheme;

[0032]FIG. 9 shows a block diagram of a color projection system of thepresent invention;

[0033]FIG. 9A shows a color wheel of the present invention; and

[0034]FIG. 10 shows a block diagram of the shadowless follow spotembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0035] The preferred embodiment herein begins with a brief descriptionof controllable mirror devices, and the way in which thecurrently-manufactured devices operate.

[0036] Work on semiconductor-based devices which tune thecharacteristics of light passing therethrough has been ongoing since the1970's. There are two kinds of known digital micromirror devices. Afirst type was originally called the formal membrane display. This firsttype used a silicon membrane that was covered with a metalized polymermembrane. The metalized polymer membrane operated as a mirror.

[0037] A capacitor or other element was located below the metalizedelement. When the capacitor was energized, it attracted the polymermembrane and changed the direction of the resulting reflection.

[0038] More modern elements, however, use an electrostatically deflectedmirror which changes in position in a different way. The mirror of thepresent invention, developed and available from Texas Instruments, Inc.uses an aluminum mirror which is sputter-deposited directly onto awafer.

[0039] The individual mirrors are shown in FIG. 1. Each individualmirror includes a square mirror plate 100 formed of reflective aluminumcantilevered on hollow aluminum post 102 on flexible aluminum beams.Each of these mirrors 100 have two stop positions: a landing electrode,which allows them to arrive into a first position shown in FIG. 2, andanother electrode against which the mirror rests when in itsnon-deflected position. These mirrors are digital devices in the sensethat there two “allowable” positions are either in a first positionwhich reflects light to the lens and hence to the illuminated object,and a second position where the light is reflected to a scatteredposition. Light scattering (i.e. selective light reflection) of thistype could also be done with other means, i.e. selectively polarizablepolymers, electronically-controlled holograms, light valves, or anyother means.

[0040] The operation of the dark field projection optics which is usedaccording to the preferred micromirror device is shown in FIG. 3. Thetwo bi-stable positions of the preferred devices are preferably plus orminus 10% from the horizontal.

[0041] An incoming illumination bundle 303 is incident at an arc of lessthan 20E on the digital micromirror device 220. The illumination bouncesoff the mirrors in one of two directions 230 or 232 depending on themirror position. In the first direction 302, the position we call “on”,the information is transmitted in the 0E direction 300 towards lens 302which focuses the information to the desired location 304. In the seconddirection of the mirror, the position we call “off”, the information isdeflected away from the desired location to the direction 306.

[0042] The human eye cannot perceive actions faster than about {fraction(1/30)} second. Importantly, the mirror transit time from tilted left totilted right is on the order of 10 Fs. This allows the pixels to bechanged in operation many orders of magnitude faster than the humaneye's persistence of vision.

[0043] Light source 310 used according to the present invention ispreferably a high intensity light source such as a xenon or metal halidebulb of between 600 and 1000 watts. The bulb is preferably surrounded bya reflector of the parabolic or ellipsoidal type which directs theoutput from bulb 300 along a first optical incidence path 305.

[0044] The preferred embodiment of the invention provides a colorcross-fading system 315, such as described in my U.S. Pat. No.5,426,476. Alternately, however, any other color changing system couldbe used. This cross-fading system adjusts the color of the light. Thelight intensity may also be controlled using any kind of associateddimmer; either electronic, mechanical or electromechanical means. Morepreferably, the DMD 320 could be used to control beam intensity asdescribed herein.

[0045] The light beam projected 310 along path 305 is incident to thedigital light altering device embodied as DMD 320, at point 322. The DMDallows operations between two different states. When the mirror in theDMD is pointed to the right, the right beam is reflected along path 325to projection/zoom lens combination 330, 332. The zoom lens combination330, 332 is used to project the image from the DMD 320 onto the objectof illumination, preferably a stage. The size and sharpness quality ofthe image can therefore be adjusted by repositioning of the lens. Whenthe mirror is tilted to the right, the light beam is projected along thelight path 335, away from projection lens 330/332. The pixels which havelight beams projected away from the lens appear as dark points in theresulting image. The dark spots are not displayed on the stage.

[0046] This DMD system reflects information from all pixels. Hence,minimal energy is absorbed in the DMD itself or any of the other optics.The device still may get hot, however not nearly as hot as the liquidcrystal gobos. Cooling 325 may still be necessary. The DMDs can becooled using any of the techniques described in (Bornhorst LCD), or by aheat sink and convection, or by blowing cold air from a refrigerationunit across the device. More preferably, a hot or cool mirror can beused in the path of the light beam to reflect infrared out of the lightbeam to minimize the transmitted heat. FIG. 3 shows hot mirror 330reflecting infra red 332 to heat sink 334. A cold mirror would be usedwith a folded optical path.

[0047] This basic system allows selecting a particular aperture shapewith which to which pass the light. That shape is then defined in termsof pixels, and these pixels are mapped to DMD 320. The DMD selectivelyreflects light of the properly-shaped aperture onto the stage. The restof the light is reflected away.

[0048] The micromirror can be switched between its positions inapproximately 10 Fs. A normal time for frame refresh rate, which takesinto account human persistence of vision, is {fraction (1/60)}th of asecond or 60 hertz. Various effects can be carried out by modulating theintensity of each mirror pixel within that time frame.

[0049] The monolithic integration which is being formed by TexasInstruments includes associated row and column decoders thereon.Accordingly, the system of the present invention need not include thoseas part of its control system.

[0050] Detailed operation of DMD 320 is shown in FIG. 4. The source beamis input to the position 322 which transmits the information eithertowards the stage along path 325 or away from the stage along path 335.

[0051] The various effects which are usable according to the presentinvention include automatic intensity dimming, use of a “shadowlessfollow spot”, hard or soft beam edges, shutter cut simulation, gobocross fading, gobo special effects, stroboscopic effects, color gobos,rotating gobos including absolute position and velocity control, andother such effects and combinations thereof. All of these effects can becontrolled by software running on the processor device. Importantly, thecharacteristics of the projected beam (gobo shape, color etc) can becontrolled by software. This enables any software effect which could bedone to any image of any image format to be done to the light beam. Thesoftware that is used is preferably image processing software such asAdobe Photoshop™, Kai's power tools™ or the like which are used tomanipulate images. Any kind of image manipulation can be mapped to thescreen. Each incremental changes to the image can be mapped to thescreen as it occurs.

[0052] Another important feature of the gobo is its ability to projectunconnected shapes that cannot be formed by a stencil. An example is twoconcentric circles. A concentric circle gobo needs physical connectionbetween the circles. Other unconnected shapes which are capable ofrendering as an image can also be displayed.

[0053] The effects carried out by the software are grouped into threedifferent categories: an edge effects processing; an image shapeprocessing; and a duty cycle processing.

[0054] The overall control system is shown in block diagram form in FIG.5. Microprocessor 500 operates based on a program which executes, interalia, the flowchart of FIG. 6. The light shape altering operatesaccording to a stencil outline. This stencil outline can be any image orimage portion. An image from image source 552 is input to a formatconverter 552 which converts the image from its native form into digitalimage that is compatable with storage on a computer. The preferreddigital image formats include a bitmap format or compressed bitmap formsuch as the GIF, JPEG, PCX format (1 bit per pixel) file, a “BMP” file(8 bits/pixel B/W or 24 bits/pixel color) or a geometric description(vectorized image). Moving images could also be sent in any animationformat such as MPEG or the like. It should be understood that any imagerepresentation format could be used to represent the image, and that anyof these representations can be used to create information that canmodify reflecting positions of the array of reflecting devices. Thepresent specification uses the term “digital representation” togenerically refer to any of these formats that can be used to representan image, and are manipulable by computers.

[0055] Image 554 is input into a working memory 556. BMP formatrepresents each “pixel” picture element of the image by a number ofbits. A typical gray scale bit map image has 8 bits representing eachpixel. A colored image of this type has 8 bits representing each of red,green, and blue representations. This color representation is called a24-bit representation, since 24-bits are necessary for each pixel. Thedescription herein will be given with reference to gray scale imagesalthough it should be understood that this system can also be used withcolor images by forming more detailed maps of the information. Bit mapsare easiest to process, but extremely wasteful of storage space.

[0056] Each memory area, representing each pixel, therefore, has 8 bitstherein. The memory 556 is 576×768 area, corresponding to the number ofmirror elements in the preferred use.

[0057] This image is defined as image No. x, and can be stored innon-volatile memory 520 (e.g., flash RAM or hard disk) for later recalltherefrom. An important feature of the present invention is that theimages are stored electronically, and hence these images can also beelectronically processed in real time using image processing software.Since the preferred mode of the present invention manipulates the imageinformation in bitmap form, this image processing can be carried out ina very quick succession.

[0058] The image to be projected is sent, by processor 500, over channel560, to VRAM 570. Line driver 562 and line receiver 564 buffer thesignal at both ends. The channel can be a local bus inside the lampunit, or can be a transmission line, such as a serial bus. The imageinformation can be sent in any of the forms described above. Standardand commonly available image processing software is available to carryout many functions described herein. These include for example,morphing, rotating, scaling, edge blurring, and other operations thatare described herein. Commercial image processing can use “Kai's PowerTools”, “CorelDraw!”, or “Morph Studio” for example. These functions areshown with reference to the flowchart of FIG. 6.

[0059] Step 600 represents the system determining the kind of operationwhich has been requested: between edge processing, image processing, andduty cycle processing. The image processing operations will be definedfirst. Briefly stated, the image processing operations include rotationof the image, image morphing from image 1 to image 2, dynamic control ofimage shape and special effects. Each of these processing elements canselect the speed of the processing to effectively time-slice the image.The morphing of the present invention preferably synchronizes keyframesof the morph with desired time slices.

[0060] Step 602 defines the operation. As described above, thisoperation can include rotation, position shift, and the like. Step 604defines the time or velocity of operation. This time can be ending timefor all or part of the movement, or velocity of the movement. Note thatall of the effects carried out in step 602 require moving some part ofthe image from one position to another.

[0061] Step 606 determine the interval of slicing, depending on thevelocity. It is desireable to slice an appropriate amount such that theuser does not see jerky motion. Ideally, in fact, we could slicemovement of the image one pixel at a time, but this is probablyunnecessary for most applications. One hundred pixel slicing is probablysufficient for all applications. The pixel slices are selected at step606.

[0062] Step 608 calculates using the time or velocity entered at step604 to determine the necessary time for operation based on the amount ofposition shift for rotation over 100 pixel slices. This is done asfollows. Position shift, rotate, and sprite animation are all simplemovements. In both, the points of the image which define the gobo shapemove over time. It is important, therefore, to decide how much movementthere is and how much time that movement will take. A rate of change ofpoints or velocity is then calculated. Of course velocity need not becalculated if it has already been entered at step 604.

[0063] Having velocity of movement and pixels per second, the timebetween slices is calculated using 100 pixels per slice divided by thevelocity in pixels per second. The direction of movement is defined bythis operation.

[0064] Therefore, the image is recalculated at step 610 for each timeinterval. This new image becomes the new gobo stencil at the newlocation. That is to say, the outline of the image is preferably used asthe gobo—light within the image is passed, and light outside the imageis blocked. In the color embodiment described herein, more sophisticatedoperations can be carried out on the image. For example, this is notlimited to stencil images, and could include for example concentriccircles or letter text with font selection.

[0065] At any particular time, the image in the VRAM 570 is used as thegobo stencil. This is carried out as follows. Each element in the imageis a gray scale of 8-bits. Each {fraction (1/60)}th of a second istime-sliced into 256 different periods. Quite conveniently, the 8-bitpixel image corresponds to 28=256.

[0066] A pixel value of 1 indicates that light at the position of thepixel will be shown on the stage. A pixel value of zero indicates thatlight at the position of the pixel will not be shown on the stage. Anygray scale value means that only part of the intensity pixel will beshown (for only part of the time of the {fraction (1/60)}th of a secondtime slice). Hence, each element in the memory is applied to one pixelof the DMD, e.g. one or many micromirrors, to display that one pixel onthe stage.

[0067] When edge processing is selected at step 600, control passes tothe flowchart of FIG. 7. The edge graying can be selected as either agradual edge graying or a more abrupt edge graying. This includes onearea of total light, one area of only partial light, and one area of nolight. The intensity of the gray scaled outline is continuously gradedfrom full image transmission to no image transmission. The intensityvariation is effected by adjusting the duty cycle of the on and offtimes.

[0068] Step 700 obtains the image and defines its outlines. This iscarried out according to the present invention by determining theboundary point between light transmitting portions (1's) and lightblocking portions (0's). The outline is stretched in all directions atstep 702 to form a larger but concentric image—a stretched image.

[0069] The area between the original image and the stretched image isfilled with desired gray scale information. Step 704 carries this outfor all points which are between the outline and the stretch image.

[0070] This new image is sent to memory 570 at step 706. As describedabove, the image in the memory is always used to project theimage-shaped information. This uses standard display technology wherebythe display system is continually updated using data stored in thememory.

[0071] The duty cycle processing in the flowchart of FIG. 6 is used toform strobe effects and/or to adjust intensity. In both cases, the imageis stored in memory and removed from memory at periodic intervals. Thisoperation prevents any light from being projected toward the stage atthose intervals, and is hence referred to as masking. When the image ismasked, all values in the memory become zero, and hence this projectsall black toward the source. This is done for a time which is shorterthan persistence of vision, so the information cannot be perceived bythe human eye. Persistence of vision averages the total light impingingon the scene.

[0072] The eye hence sees the duty cycle processing as a differentintensity.

[0073] The stroboscopic effect turns on and off the intensity, rangingfrom about 1 Hz to 24 Hz. This produces a strobe effect.

[0074] These and other image processing operations can be carried out:(1) in each projection lamp based on a pre-stored or downloaded command;(2) in a main processing console; or (3) in both.

[0075] Another important aspect of the invention is based on theinventor's recognition of a problem that has existed in the art of stagelighting. Specifically, when a performer is on the stage, a spotlightilluminates the performer's area. However, the inventor of the presentinvention recognized a problem in doing this. Specifically, since wewant to see the performer, we must illuminate the performer's area.However, when we illuminate outside the performer's area, it casts ashadow on the stage behind the performer. In many circumstances, thisshadow is undesirable.

[0076] It is an object of this embodiment to illuminate an area of thestage confined to the performer, without illuminating any locationoutside of the performer's area. This is accomplished according to thepresent invention by advantageous processing structure which forms a“shadowless follow spot”. This is done using the basic block diagram ofFIG. 10.

[0077] The preferred hardware is shown in FIG. 10. Processor 1020carries out the operations explained with reference to the followingflowcharts which define different ways of following the performer. Inall of these embodiments, the shape of the performer on the stage isdetermined. This can be done by (1) determining the performer's shape bysome means, e.g. manual, and following that shape; (2) correlating overthe image looking for a human body shape; (3) infra red detection of theperformer's location followed by expanding that location to the shape ofthe performer; (4) image subtraction; (5) detection of special indiceson the performer, e.g. an ultrasonic beacon, or, any other techniqueeven manual following of the image by, for example, an operatorfollowing the performer's location on a screen using a mouse.

[0078]FIG. 8A shows a flowchart of (1) above. At step 8001, theperformer is located within the image. The camera taking the image ispreferably located at the lamp illuminating the scene in order to avoidparallax. The image can be manually investigated at each lamp ordownloaded to some central processor for this purpose.

[0079] Once identified, the borders of the performer are found at 8005.Those borders are identified, for example, by abrupt color changes nearthe identified point. At step 8010, those changes are used to define a“stencil” outline that is slightly smaller than the performer at 8010.That stencil outline is ued as a gobo for the light at 8015.

[0080] The performer continues to move, and at 8020 the processorfollows the changing border shape. The changing border shape produces anew outline which is fed to 8010 at which time a new gobo stencil isdefined.

[0081] Alternative (2) described above is a correlation technique. Aflowchart of this operation is shown in FIG. 8B. At step 8101, thecamera obtains an image of the performer, and the performer isidentified within that image. That image issued as a kernel for furtherlater correlation. The entire scene is obtained at step 8105. The wholescene is correlated against the kernel at 8110. This uses known imageprocessing techniques.

[0082] The above can be improved by (3), wherein infra red detectiongives the approximate area for the performer.

[0083] As explained in previous embodiments, the DMD is capable ofupdating its position very often: for example, 106 times a second. Thisis much faster than any real world image can move. Thirty times a secondwould certainly be sufficient to image the performer's movements.Accordingly, the present invention allows setting the number of frameupdates per second. A frame update time of 30 per second is sufficientfor most applications. This minimizes the load on the processor, andenables less expensive image processing equipment to be used.

[0084]FIG. 8C shows the image subtracting technique.

[0085] First, we must obtain a zeroing image. Therefore, the first stepat step 800, is to obtain an image of the stage without the performer(s)thereon. This zero image represents what the stage will look like whenthe performers are not there.

[0086] Between processing iterations, the processor can carry out otherhousekeeping tasks or can simply remain idle.

[0087] Step 802 represents the beginning of a frame update. An image isacquired from the video camera 550 at step 804. The image is stillpreferably arranged in units of pixels, with each pixel including avalue of intensity and perhaps red, green, and blue for that pixel.

[0088] At step 806 subtracts the current image from the zeroed image.The performer image that remains is the image of the performer(s) andother new elements on the stage only. The computer determines at thistime which part of that image we want to use to obtain the shadowlessfollow spot. This is done at step 808 by correlating the image thatremains against a reference, to determine the proper part of the imageto be converted into a shadowless follow spot. The image of theperformer is separated from other things in the image. Preferably it isknown for example what the performer will wear, or some image of aunique characteristic of the performer has been made. That uniquecharacteristic is correlated against the performer image to determinethe performer only at the output of step 808. This image is digitized atstep 810: that is all parts of this image which are not performer areset to zeros so that light at those positions is reflected. In this way,a gobo-like image is obtained at step 810, that gobo-like image being achanging cutout image of the performer. An optional step 812 furtherprocesses this image to remove artifacts, and preferably to shrink theimage slightly so that it does not come too close to the edge of theperformer's outline. This image is then transferred to the VRAM at step814, at which time it is reentered into the DMD 1012 to form a gobo-likemask for the lamp. This allows the light to be appropriately shaped toagree with the outline of the performer 1004.

[0089] Another embodiment of the present invention uses the abovedescribed techniques and basic system of the present invention toprovide color to the lamp gobo. This is done using techniques that werepostulated in the early days of color tv, and which now find a reneweduse. This system allows colored gobos, and more generally, allows -anyvideo image to be displayed.

[0090]FIG. 9 shows the lamp 310 in a series with a rotating multicoloreddisk 902. FIG. 9a shows the three sectors of the disk. Red sector 950, ablue sector 952, and a green sector 954. The light along the opticalpath 902 is colored by passing through one of these three quadrants, andthen through DMD 320. DMD 320 is driven by a rotating source 910,synchronized with the operation of spinning of the color disk 902. Thevideo is driven to produce a red frame, then a green frame, then a blueframe, one after another, for example. The red filtered video istransferred at the same moment when the red sector 950 is in the lightpath. So as long as the different colors are switched faster than theeye's persistence of vision, the eye will average them together to see afull color scene.

[0091] Although only a few embodiments have been described in detailabove, those having ordinary skill in the art will certainly understandthat many modifications are possible in the preferred embodiment withoutdeparting from the teachings thereof.

[0092] All such modifications are intended to be encompassed within thefollowing claims.

[0093] For example, any direction deflecting device could be used inplace of the DMD. A custom micro mirror device would be transparent, andhave thin mirrors that “stowed” at 90E to the light beam to allow thebeam to pass, and turned off by moving to a reflecting position toscatter select pixels of the light beam. The color changing devicescould be any device including dichroics.

What is claimed is:
 1. A light shape altering device, having elementswhich selectively modify light, located in the path of a light beam andcomprising: a first selective light reflection device, having aplurality of elements, each element defining a portion of an image, andeach element being separately controllable between a first state whichpasses light to a desired object of illumination and a second statewhich reflects light away from the desired object of illumination; and acontroller which obtains a desired shape and which converts said shapeinto control signals for said first selective light reflection device,so that said selective light reflective device passes light of apredetermined shape to said desired object of illumination.